Semiconductor wafers, in particular semiconductor wafers of monocrystalline silicon, are needed as basic materials for the production of electronic components. The manufacturers of such components require that the delivered semiconductor wafers have front and back sides which are as far as possible planar and parallel to one another. In order to meet this requirement, a processing step for the production of such semiconductor wafers conventionally comprises polishing thereof. Double-side polishing (DSP), in which the front side and the back side of the semiconductor wafer are simultaneously polished in the presence of a polishing agent, is particularly suitable. During DSP, the semiconductor wafer is located together with further semiconductor wafers in a gap between a lower polishing pad and an upper polishing pad. Each of the polishing pads covers a corresponding lower and upper polishing plate. The semiconductor wafers lie during the DSP in openings of carriers, which guide and protect them. The carriers are externally toothed disks, which are arranged between an inner and an outer toothed wheel or pin gear of the polishing device. A toothed wheel or pin gear will be referred to below as a drive gear. During polishing, the carriers are set in a rotational movement about their middle and the middle of the polishing plates by the inner drive gear or by the inner and outer drive gears. Furthermore, the polishing plates are usually also rotated in countersense about their axes, which results in kinematics characteristic of DSP, in which a point on a semiconductor wafer side to be polished follows a cycloid path on the corresponding polishing pad.
Before first use and after a certain degree of wear is reached, it is usual to dress the lower and upper polishing pads. During the dressing, the surface of the polishing pad is roughened and slight material abrasion is induced in order to impart a favourable working state to the polishing pad.
According to U.S. Patent Publication No. 2012/0189777, it is advantageous to subject the polishing plates to shaped dressing (“truing”), so that the gap between the polishing pads is as far as possible uniformly wide. Furthermore, it is described therein that, in order to dress the polishing pads, the carriers are replaced by dressing rings. The dressing is carried out in the presence of a cooling lubricant, the dressing rings being moved over the lower and upper polishing pads, in the absence of inserted semiconductor wafers, in a movement similar to the kinematics of the DSP.